/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    RemoveFolds.java
 *    Copyright (C) 1999 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.instance;

import weka.core.Capabilities;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.RevisionUtils;
import weka.core.Utils;
import weka.core.Capabilities.Capability;
import weka.filters.Filter;
import weka.filters.UnsupervisedFilter;

import java.util.Enumeration;
import java.util.Random;
import java.util.Vector;

/**
 * <!-- globalinfo-start --> This filter takes a dataset and outputs a specified
 * fold for cross validation. If you want the folds to be stratified use the
 * supervised version.
 * <p/>
 * <!-- globalinfo-end -->
 * 
 * <!-- options-start --> Valid options are:
 * <p/>
 * 
 * <pre>
 * -V
 *  Specifies if inverse of selection is to be output.
 * </pre>
 * 
 * <pre>
 * -N &lt;number of folds&gt;
 *  Specifies number of folds dataset is split into. 
 *  (default 10)
 * </pre>
 * 
 * <pre>
 * -F &lt;fold&gt;
 *  Specifies which fold is selected. (default 1)
 * </pre>
 * 
 * <pre>
 * -S &lt;seed&gt;
 *  Specifies random number seed. (default 0, no randomizing)
 * </pre>
 * 
 * <!-- options-end -->
 * 
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 5548 $
 */
public class RemoveFolds extends Filter implements UnsupervisedFilter,
		OptionHandler {

	/** for serialization */
	static final long serialVersionUID = 8220373305559055700L;

	/** Indicates if inverse of selection is to be output. */
	private boolean m_Inverse = false;

	/** Number of folds to split dataset into */
	private int m_NumFolds = 10;

	/** Fold to output */
	private int m_Fold = 1;

	/** Random number seed. */
	private long m_Seed = 0;

	/**
	 * Gets an enumeration describing the available options..
	 * 
	 * @return an enumeration of all the available options.
	 */
	public Enumeration listOptions() {

		Vector newVector = new Vector(6);

		newVector.addElement(new Option(
				"\tSpecifies if inverse of selection is to be output.\n", "V",
				0, "-V"));

		newVector.addElement(new Option(
				"\tSpecifies number of folds dataset is split into. \n"
						+ "\t(default 10)\n", "N", 1, "-N <number of folds>"));

		newVector.addElement(new Option(
				"\tSpecifies which fold is selected. (default 1)\n", "F", 1,
				"-F <fold>"));

		newVector
				.addElement(new Option(
						"\tSpecifies random number seed. (default 0, no randomizing)\n",
						"S", 1, "-S <seed>"));

		return newVector.elements();
	}

	/**
	 * Parses a given list of options.
	 * <p/>
	 * 
	 * <!-- options-start --> Valid options are:
	 * <p/>
	 * 
	 * <pre>
	 * -V
	 *  Specifies if inverse of selection is to be output.
	 * </pre>
	 * 
	 * <pre>
	 * -N &lt;number of folds&gt;
	 *  Specifies number of folds dataset is split into. 
	 *  (default 10)
	 * </pre>
	 * 
	 * <pre>
	 * -F &lt;fold&gt;
	 *  Specifies which fold is selected. (default 1)
	 * </pre>
	 * 
	 * <pre>
	 * -S &lt;seed&gt;
	 *  Specifies random number seed. (default 0, no randomizing)
	 * </pre>
	 * 
	 * <!-- options-end -->
	 * 
	 * @param options
	 *            the list of options as an array of strings
	 * @throws Exception
	 *             if an option is not supported
	 */
	public void setOptions(String[] options) throws Exception {

		setInvertSelection(Utils.getFlag('V', options));
		String numFolds = Utils.getOption('N', options);
		if (numFolds.length() != 0) {
			setNumFolds(Integer.parseInt(numFolds));
		} else {
			setNumFolds(10);
		}
		String fold = Utils.getOption('F', options);
		if (fold.length() != 0) {
			setFold(Integer.parseInt(fold));
		} else {
			setFold(1);
		}
		String seed = Utils.getOption('S', options);
		if (seed.length() != 0) {
			setSeed(Integer.parseInt(seed));
		} else {
			setSeed(0);
		}
		if (getInputFormat() != null) {
			setInputFormat(getInputFormat());
		}
	}

	/**
	 * Gets the current settings of the filter.
	 * 
	 * @return an array of strings suitable for passing to setOptions
	 */
	public String[] getOptions() {

		String[] options = new String[8];
		int current = 0;

		options[current++] = "-S";
		options[current++] = "" + getSeed();
		if (getInvertSelection()) {
			options[current++] = "-V";
		}
		options[current++] = "-N";
		options[current++] = "" + getNumFolds();
		options[current++] = "-F";
		options[current++] = "" + getFold();
		while (current < options.length) {
			options[current++] = "";
		}
		return options;
	}

	/**
	 * Returns a string describing this filter
	 * 
	 * @return a description of the filter suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String globalInfo() {
		return "This filter takes a dataset and outputs a specified fold for "
				+ "cross validation. If you want the folds to be stratified use the "
				+ "supervised version.";
	}

	/**
	 * Returns the tip text for this property
	 * 
	 * @return tip text for this property suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String invertSelectionTipText() {

		return "Whether to invert the selection.";
	}

	/**
	 * Gets if selection is to be inverted.
	 * 
	 * @return true if the selection is to be inverted
	 */
	public boolean getInvertSelection() {

		return m_Inverse;
	}

	/**
	 * Sets if selection is to be inverted.
	 * 
	 * @param inverse
	 *            true if inversion is to be performed
	 */
	public void setInvertSelection(boolean inverse) {

		m_Inverse = inverse;
	}

	/**
	 * Returns the tip text for this property
	 * 
	 * @return tip text for this property suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String numFoldsTipText() {

		return "The number of folds to split the dataset into.";
	}

	/**
	 * Gets the number of folds in which dataset is to be split into.
	 * 
	 * @return the number of folds the dataset is to be split into.
	 */
	public int getNumFolds() {

		return m_NumFolds;
	}

	/**
	 * Sets the number of folds the dataset is split into. If the number of
	 * folds is zero, it won't split it into folds.
	 * 
	 * @param numFolds
	 *            number of folds dataset is to be split into
	 * @throws IllegalArgumentException
	 *             if number of folds is negative
	 */
	public void setNumFolds(int numFolds) {

		if (numFolds < 0) {
			throw new IllegalArgumentException(
					"Number of folds has to be positive or zero.");
		}
		m_NumFolds = numFolds;
	}

	/**
	 * Returns the tip text for this property
	 * 
	 * @return tip text for this property suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String foldTipText() {

		return "The fold which is selected.";
	}

	/**
	 * Gets the fold which is selected.
	 * 
	 * @return the fold which is selected
	 */
	public int getFold() {

		return m_Fold;
	}

	/**
	 * Selects a fold.
	 * 
	 * @param fold
	 *            the fold to be selected.
	 * @throws IllegalArgumentException
	 *             if fold's index is smaller than 1
	 */
	public void setFold(int fold) {

		if (fold < 1) {
			throw new IllegalArgumentException(
					"Fold's index has to be greater than 0.");
		}
		m_Fold = fold;
	}

	/**
	 * Returns the tip text for this property
	 * 
	 * @return tip text for this property suitable for displaying in the
	 *         explorer/experimenter gui
	 */
	public String seedTipText() {

		return "the random number seed for shuffling the dataset. If seed is negative, shuffling will not be performed.";
	}

	/**
	 * Gets the random number seed used for shuffling the dataset.
	 * 
	 * @return the random number seed
	 */
	public long getSeed() {

		return m_Seed;
	}

	/**
	 * Sets the random number seed for shuffling the dataset. If seed is
	 * negative, shuffling won't be performed.
	 * 
	 * @param seed
	 *            the random number seed
	 */
	public void setSeed(long seed) {

		m_Seed = seed;
	}

	/**
	 * Returns the Capabilities of this filter.
	 * 
	 * @return the capabilities of this object
	 * @see Capabilities
	 */
	public Capabilities getCapabilities() {
		Capabilities result = super.getCapabilities();
		result.disableAll();

		// attributes
		result.enableAllAttributes();
		result.enable(Capability.MISSING_VALUES);

		// class
		result.enableAllClasses();
		result.enable(Capability.MISSING_CLASS_VALUES);
		result.enable(Capability.NO_CLASS);

		return result;
	}

	/**
	 * Sets the format of the input instances.
	 * 
	 * @param instanceInfo
	 *            an Instances object containing the input instance structure
	 *            (any instances contained in the object are ignored - only the
	 *            structure is required).
	 * @return true because outputFormat can be collected immediately
	 * @throws Exception
	 *             if the input format can't be set successfully
	 */
	public boolean setInputFormat(Instances instanceInfo) throws Exception {

		if ((m_NumFolds > 0) && (m_NumFolds < m_Fold)) {
			throw new IllegalArgumentException(
					"Fold has to be smaller or equal to " + "number of folds.");
		}
		super.setInputFormat(instanceInfo);
		setOutputFormat(instanceInfo);
		return true;
	}

	/**
	 * Input an instance for filtering. Filter requires all training instances
	 * be read before producing output.
	 * 
	 * @param instance
	 *            the input instance
	 * @return true if the filtered instance may now be collected with output().
	 * @throws IllegalStateException
	 *             if no input structure has been defined
	 */
	public boolean input(Instance instance) {

		if (getInputFormat() == null) {
			throw new IllegalStateException("No input instance format defined");
		}
		if (m_NewBatch) {
			resetQueue();
			m_NewBatch = false;
		}
		if (isFirstBatchDone()) {
			push(instance);
			return true;
		} else {
			bufferInput(instance);
			return false;
		}
	}

	/**
	 * Signify that this batch of input to the filter is finished. Output() may
	 * now be called to retrieve the filtered instances.
	 * 
	 * @return true if there are instances pending output
	 * @throws IllegalStateException
	 *             if no input structure has been defined
	 */
	public boolean batchFinished() {

		if (getInputFormat() == null) {
			throw new IllegalStateException("No input instance format defined");
		}

		Instances instances;

		if (!isFirstBatchDone()) {
			if (m_Seed > 0) {
				// User has provided a random number seed.
				getInputFormat().randomize(new Random(m_Seed));
			}
			// Push instances for output into output queue

			// Select out a fold
			if (!m_Inverse) {
				instances = getInputFormat().testCV(m_NumFolds, m_Fold - 1);
			} else {
				instances = getInputFormat().trainCV(m_NumFolds, m_Fold - 1);
			}
		} else {
			instances = getInputFormat();
		}

		flushInput();

		for (int i = 0; i < instances.numInstances(); i++) {
			push(instances.instance(i));
		}

		m_NewBatch = true;
		m_FirstBatchDone = true;
		return (numPendingOutput() != 0);
	}

	/**
	 * Returns the revision string.
	 * 
	 * @return the revision
	 */
	public String getRevision() {
		return RevisionUtils.extract("$Revision: 5548 $");
	}

	/**
	 * Main method for testing this class.
	 * 
	 * @param argv
	 *            should contain arguments to the filter: use -h for help
	 */
	public static void main(String[] argv) {
		runFilter(new RemoveFolds(), argv);
	}
}
